UPPER AIR MAPS
Change of Air Pressure with Height Page: 12 FIGURE 1.10 Atmospheric pressure decreases rapidly with height. Climbing to an altitude of only 5.5 km, where the pressure is 500 mb, would put you above one-half of the atmosphere’s molecules.
Page: 207 FIGURE 8.12 When there are no horizontal variations in pressure, constant pressure surfaces are parallel to constant height surfaces. In the diagram, a measured pressure of 500 millibars is 5600 meters above sea level everywhere. The actual atmosphere extends well above the tropopause level shown here. (Dots in the diagram represent air molecules.)
Pressure = 500 mb Warm air is less dense (“thicker”) than cold air. Page: 207 FIGURE 8.13 The area shaded gray in the above diagram represents a surface of constant pressure, or isobaric surface. Because of the changes in air density, the isobaric surface rises in warm, less-dense air and lowers in cold, more-dense air. Where the horizontal temperature changes most quickly, the isobaric surface changes elevation most rapidly. Warm air is less dense (“thicker”) than cold air.
Strongest Winds Page: 208 FIGURE 8.14 Changes in altitude of an isobaric surface (500 mb) show up as contour lines on an isobaric (500 mb) map. Where the isobaric surface dips most rapidly, the contour lines are closer together on the 500-mb map.
Three-Dimensional Depiction of an Upper Air Constant Height Surface Page: 208 FIGURE 8.15 The wavelike patterns of an isobaric surface reflect the changes in air temperature. An elongated region of warm air aloft shows up on an isobaric map as higher heights and a ridge; the colder air shows as lower heights and a trough.
L H Cold Cold Warm Trough Ridge Surface Low Surface High Page: 274 FIGURE 2 The circulation of the air aloft is in the form of waves—troughs and ridges—that encircle the globe. Warm Surface lows form downstream of upper air troughs. Surface highs form downstream of upper air ridges.
Jet Streams COLD WARM WARM WARM (Chap. 8, pp. 206–210) Page: 275 FIGURE 10.12 A jet stream is a swiftly flowing current of air that moves in a wavy west-to-east direction. The figure shows the position of the polar jet stream and subtropical jet stream in winter. Although jet streams are shown as one continuous river of air, in reality they are discontinuous, with their position varying from one day to the next. (Chap. 8, pp. 206–210)
CLOUD CLASSIFICATION
Basic Cloud Types FIGURE 5.24 A generalized illustration of basic cloud types based on height above the surface and vertical development.
CIRRUS
CIRROCUMULUS
CIRROSTRATUS
ALTOCUMULUS
ALTOCUMULUS
ALTOSTRATUS
STRATOCUMULUS
STRATUS
NIMBOSTRATUS
CUMULUS HUMILIS (FAIR WEATHER CUMULUS)
CUMULUS HUMILIS
CUMULUS CONGESTUS (IN BACKGROUND) CUMULUS HUMILIS (IN FOREGROUND)
CUMULUS CONGESTUS
CUMULONIMBUS
CUMULONIMBUS
TABLE 5.3 Approximate Height of Cloud Bases Above the Surface for Various Locations The same type of cloud will typically be at a lower altitude in the polar regions and higher in the tropics. (Chap. 5, pp. 127–135)
Nerdy Cloud Classification Details Just like animals and plants, clouds are classified according to their genus, species, and variety. 1. Genera: e.g., stratus, cumulonimbus (the types discussed today) 2. Species: e.g., humilis, congestus, castellanus, lenticularis (later) 3. Variety: e.g., undulatus, translucidus, opacus So a cloud might be classified as altocumulus castellanus opacus. (For examples, see Table 5.4 (page 133) and https://cloudatlas.wmo.int/principles-of-cloud-classification.html )
ALTOSTRATUS